Production of benzanthrone



Patented" F eb. 7, 1933 UNITED STATES PATENT OFFICE,"

.ALEXANDER .T; woman, or WILMINGTON, DELAWARE, AssrGNoR To a x. nuro'n'r DE NEMOURS'zCOMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELA- WARE PRODUCTION 01 BEN ZAN THRONE No Drawing.

sulphuric acid. The technical method mostcommonly used consists in a reduction of v anthraquinone in sulphuric acid solution by means of copper or aluminum powder at a lowv temperature and then effecting a con densation. of the reduction product (anthra- 1101) with glycerine to form benzanthroneQ In the final analysis this procedure is a con-' densation of anthranol and glycerine. These methods are somewhat objectionable because of their comparatively low yields probably due to over-reduction, etc.

It is. an object of the present inventionnto prepare benzanthrone fromanthraquinone to obtain maximum yields. It .isva further object to carry out the reduction step of the process by Ineans'of the cheaper iron dust in place.;- of the usual copper or aluminum.

other objectswill be apparent from thedescription.

glycerine both reactions beingcarried out in a medium ofsulphuric acid. I g

Without restricting the invention thereto, the following, will serve as an example of procedure in accordance therewith 100 parts of anthraquinoneare dissolved in 93-10070 ll lphuric acid at room temperature. The solu'tion is then diluted with complete, the charge is drowned zanthrone.

product. The chemical Application filed August 19, 1827. Serial No. 214,221:

cold water until the acidity is brought down to 80-83% H SO This dilution insures almost a complete precipitation of the anthraquinone. The temperature is thengraisedto 110-115 C. While maintaining this temperature 40-45 parts of irondust (-150 mesh) and 80-90parts of distilled glycerine are slowly added simultaneously at such a rate "that both ingredients are introduced into the reaction mass in a period of from twoto four hours. The temperature is then raised slowly to 118120- C. (about onehalf to onehour) and maintained at this pointuntil no unchanged anthraquinone is shown by the usual tests. WVhen the conver sion of the anthraquinoneto benzanthrone is I p in a sufiicient amount of cold water to bring the acidity to 5-8% of HgsO 'and the precipitated benzanthrone 'is filtered off, washed, and dried. In'the aboveexample, the anthraquinoneis reduced to hydroxy-a-nthrone which immediately reacts with the glycerine to form ben- The elimination of the reduction product prevents excessive reduction and therefore results in a more uniform final reactions involved are as follows z Hydroxy-anthrone Anthraquind OH H or'lt's iso- 'meric form The final chemical reaction taking place is g As is wen known, hydroxy-anthrone and anthraquin'olare isomeric and behave in an identical manner in the conversion to benzanthrone. In the reduction of anthraquinone, according to the present invention, both isomers are produced, one being changed to the other by a readily reversible reaction.

The present process permits the use of iron dust in place of copper, aluminum or aniline sulphate. This is a distinct economic advantage, although the present process will operate very efficiently when copper or aluminum is used in place of the iron.

In the usual processes heretofore used, benzanthrone is produced from anthranol instead of hydroizy-anthrone The reduction of the anthraquinone is represented by the following Anthraduinone C 0- copper or 0 aluminum 1:

O 0 H2504 I v H V Anthtanol that obtained by the knowntechnical processes; The use of iron dust under the above conditions presents a great economic advantage in that it is possible to reduce the consumption of glycerine approximately 40 /0 of the usual requirement. V

The benzanthrone obtained according to the present process has'a freezing point of l69l70 C. and a purity of 90-93%. It is 7 highly valuable for the synthesis of a large number of vat colors commonly known as the benzanthrone vat dyes.

t will be understood that the operation of the process is not limited to. the specific details described. For instance, the dissolving of the anthraquinone in 93-100% sulphuric acid and subsequent dilution offers the most convenient practice for obtaining the anthraquinone in a finely divided state and suspended in the proper concentration of sulphuric acid. An alternative method of preparing the charge consists in dissolving the anthraquinone in sulphuric acid, precipitating by drowning, filtering and then slurrying the press cake with sulphuric acid and ad justing the acid to the proper concentration. While this is one of the preferred conditions, it is obvious that other methods may be used to obtain the same result. The dilution of the sulphuric acid to 80-83% strength is usually preferred for the present reaction,

whether iron, copper or aluminum is used as the reducing agent. Lower or higher strength of acid will produce benzanthrone but not so satisfactorily as the preferred range.

The temperatures used in the present process are susceptible of some variation, although those given are the preferred ones. The reduction is carried out at a temperature of 1101'15 C. as this temperature is about that at which the glycerine is converted to acrolein which in turn enters into the reaction with hydroXy-anthrone or anthraquinol to form the benzanthrone. If the reduction is carried out at lower temperatures, the hydroXy-anthrone and anthraquinol will ac- V cumulate and be converted to anthranol and anthrone, the very thing which the present process attempts to obviate. The present process makes use of temperatures between 118420 C. to finish the reaction in order to assure complete conversion. \Vhile these temperatures and higher may be used at the start of the reaction, it is found that these temperatures will result in too rapid a reaction and will not permit proper controlof the process.

Suitable changes may be made in carrying out the process without departingfrom the spirit and scope of the invention, except as limited by the appended claims.

I claim 1. The process for producing benzanthrone which comprises suspending anthraquinone in concentrated sulphuric acid and heating the suspension while simultaneously adding glycerine and a metallic reducing agent from the group consisting of iron, copper and aluminum, at a temperature of l10120 C.

2.. The process for producing benzanthrone which comprises suspending anthraquinone in concentrated sulphuric acid and heating thesuspension while simultaneously adding glycerine and a metallic reducing the group consisting of iron, copper and aluminum, at a temperature of 110115 C. 3. The process for producing benzanthrone which comprises suspending anthraquinone in concentrated the suspension while simultaneously adding glycerine and iron at a temperature of 110-120 O.

i. The process for producing benzanthrone which comprises suspending anthraquinone in concentrated sulphuric acid and heating the suspension while simultaneously adding glycerine and iron at a temperature of 110-115 G.

ioo

agent from sulphuric acid and heating 5. The process for producing benzanthrone M which comprises reducing ant raquinone by means of iron, and Condensing the reduction product with glycerine, both reactions being carried out simultaneously in a sulphuric acid 1 medium heated to temperatures of about 7. The process for producing benzanthrone which comprises suspending anthraquinone in -83% sulphuric acid and heating the suspension while simultaneously adding glycerine and a metallic reducing agent 0 the group consisting of iron, copper and aluminum, the temperatures of the suspension being maintainedat about 110120 C.

8. The process for producing benzan throne which comprises suspending anthraquinone in 8083% sulphuric acid and heating the suspension while simultaneously adding glycerine and'iron, thetemperatures of the suspension being maintained at about 110120 C. I

9. The process for producing benzanthrone which comprises suspendinganthraquinone in concentrated sulphuric acid, reducing the anthraquinone With a finely divided metal taken from the group consisting of iron, copper and aluminum to form hydroxy-anthrone and anthraquinol, and reacting upon the reduction products with glycerine substantially as soon as they are formed in the sulphuric. acid suspension which is maintained. at temperatures of about 10. The process for producing benzanthrone which comprises suspending anthrauinone in concentrated sulphuric-acid, reducing the anthraquinone with finely divided iron to form hydroxy-anthrone and anthraquinol, and reacting upon the reduction products with glycerinesubstantially as soon as they areformed in the sulphuric acid suspension which is maintained at temperatures of about 110120 CQ 11. In the process of making benzanv throne, the step which comprisesreducing anthraquinone, in the presence of glycerine, and in a sulphuric acid medium of eater than about 80% strength, and maintained at tem peratures of about 110120 C. by means of a metal taken from the group consisting of aluminum, copper and iron.

12. In the process of making benzanthrone, the step which comprises reducing anthraquinone, in the presence of'glycerine,

and in a sulphuric acid medium of greater.

than about 80% strength, and maintained at temperatures of about 110-120 C. by means of iron. v

13. In the process of making benzanthrone, the step which comprises reducing anthraquinone, in the presence of glycerine, and in a sulphuric acid medium of greater I temperatures of about 110-120 C. by means of a finely divided metal taken from the group consisting of aluminum, copper and H011.

14. In the process of making benzanthrone, the step which comprises reducing anthraquinone, in the presence of glycerine, and in a sulphuric acid medium of greater than about 80% strength, andmaintained at temperatures of about 110120 C. by'means of finely divided iron.

15. In the process for producing benzanthrone, the step which comprises reducing anthraquinone with finely divided iron and condensing the reduction product with glycerine, both reactions being carried out simultaneously in a sulphuric acid medium of greater than about 80% strength and maintained at temperatures of about 110-120 C.

16. In the process for. producing benzanthrone, the step which comprises reducing ant-hraquinone with finely divided iron and condensing the reduction product with glycerine,'both reactions being carried out simultaneously in a sulphuric acid medium .of greater than about 80% strength and maintained at temperatures between 110l15 C.

17. The process of producing benzanthrone, which comprises suspending anthraquinone in a sulphuric acid medium, simultaneously adding glycerine and a reducing agent consisting only of a metallic substance from the group consisting of iron, copper and aluminum, and heating the suspension.

18. The process of producing benzanthrone, which comprises suspending anthraquinone in a sulphuric acid medium, simultaneously adding glycerine and a reducing agent consisting only of iron, and heating the suspension.

' In testimony whereof I aflix my signature.

. ALEXANDER J. WUERTZ. 

